Tinker Air Force Base - Oklahoma City, OK
The Water Jet is used primarily to remove rubberized coatings from engine casings. It is also capable of stripping abradable thermal spray coatings, fiberglass, paint, sealants, adhesives, and aluminum vane wraps. Modifications to the system would allow it to strip virtually all thermal spray coatings.
In the past, rubberized coatings were removed from engine cases in a two-step process. First, the case was soaked in methylene chloride for several days. The case was then removed from the solvent, and the rubber was scraped away using a putty knife. Currently, thermal spray coatings are removed in a chemical process.
Two Water Jets are currently in operation. The first is a small unit with a maximum part diameter of 36 inches. It was installed in 1987, and is operated by securing the part onto a turntable and manually directing the nozzle at the area to be stripped. The lid is then closed and the cycle is started. The machine delivers 10 gallons of water per minute at a pressure of 10,000 PSI. This unit is used to strip rubberized coating from engine cases and to remove aluminum vane wraps from the TF30 Inlet Guide Vanes.
The second machine, installed in 1993, is larger and uses robotics for nozzle placement. This machine operates at 20,000 PSI with a flow rate of 20 gallons per minute. The increased pressure allows a wider range of materials to be stripped, including abradable thermal spray coatings. Modifications to the system to allow operation between 30,000 and 50,000 PSI would add the ability to strip most thermal spray coatings. In this machine, the operator again secures the part to a turntable however, the nozzle placement is computer controlled. The nozzle movements for each part can be programmed and saved for future use.
In both systems, the tripped materials are filtered from the waste stream. The water is then discharged to the Industrial Wastewater Treatment Plant. The Water Jet technology is patented by Mike Patry and Herb Barringer, OC-ALC engineers. The equipment is manufactured by Automaker.
The Water Jets have eliminated the use of 2,360 gallons per year of methylene chloride. They have also resulted in quicker processing times and increased worker safety. The modification to allow higher operating pressure would further reduce hazardous chemical usage.